Aqueous sizing composition for glass fibers and sized glass fibers for thermoplastic reinforcement

ABSTRACT

Glass fibers reinforced polymeric polymers can be produced with high strength properties such as tensile strength, flexural strength and impact strength by using sized glass fiber strands of the present invention. The sized glass fiber strands have a residue of an aqueous sizing composition comprising: aqueous dispersible, emulsifiable, or solubilizable polyurethane polymer, polyepoxide polymer, polyethylene-containing polymer, and wax, where the weight ratio of the polyethylene containing polymer to the wax is in the range of about 25 to 1 to about 1 to 25, and one or more amino silane coupling agents. In addition to the amino silane coupling agent, the sizing composition may have an epoxy silane coupling agent and/or a lubricant modified silane coupling agent. The wax can be deleted from the composition, when the polyethylene-containing polymer has limited branching. The sized glass fiber strands can be produced by conventional forming process or by a wet chopped glass fiber forming process.

The present invention is directed to an aqueous treating composition fortreating glass fibers during their formation and treated glass fibersfor reinforcing thermoplastic polymers.

BACKGROUND OF THE INVENTION

Glass fibers have been used in various forms such as chopped filamentsand strands, continuous filaments and strands and sundry mats forreinforcing polymeric materials like thermoplastics and thermosettingmaterials. These glass fibers are produced from molten streams of glassbeing attenuated from orifices in a bushing of a glass batch meltingfurnace. After the glass fibers are formed and have cooled somewhat, anaqueous treating composition, known as a sizing composition, is appliedto the fibers to provide protection from interfilament abrasion and tomake the glass fibers more compatible with the thermoplastic orthermosetting materials they will reinforce. The glass fibers are thenchopped, or gathered into strands and chopped, or gathered into strandsto form continuous strands. The chopping process, where the fibers orstrands or groups of fibers are chopped during forming, is known as awet chop process. If the continuous glass fiber strands are subsequentlychopped, such a process is known as a dry chop process. In addition,continuous glass fiber strands can be manufactured into continuous glassfiber strand mat. Also, chopped glass fiber strand mat can be produced.All of these glass fiber products are useful in reinforcingthermoplastic and thermosetting polymeric materials to increase thestrength and other properties of the polymeric materials.

Thermoplastics are reinforced by incorporating reinforcement such asglass fibers into the thermoplastic polymer matrix. Glass fibers for usein such reinforcements originally consisted of a polymer coated glassfiber roving that was chopped into pellets. The pellets, known as "longglass" products were about 1/8 inch in diameter and about 1/4 to 1/2inch in length. The development of "short glass" products, where thechopped glass fiber strand is produced by dry chopping sized glass fiberstrand roving or producing wet chopped glass fiber strand, involveslengths of the chopped glass fiber strands from around 1/8 to 1/4 of aninch. These short glass products have allowed for the production ofreinforced thermoplastics by extrusion blending of a mixture of resinand chopped glass fibers. Reinforced thermoplastics can be prepared tocontain glass fibers in levels ranging from about 10 to 55 percent on aweight basis. With short glass products, it is possible to achieve thedesired glass content by blending moldable thermoplastic polymercontaining glass fibers with a non-reinforced moldable thermoplasticpolymer. For example, a fiber glass reinforced polymer concentratehaving a glass content of 40 percent by weight or greater can be blendedwith unreinforced polymer to achieve the desired reduced level of glassreinforcement in the blended moldable product. Thermoplastic resins thatare useful in producing reinforced thermoplastic products include suchpolymers as polyamides, polystyrenes, styrene-acrylonitrile copolymers,acrylonitrile-butadiene-styrene terpolymers, polycarbonates,polypropylenes, polyethylenes, polyacetals, polysulfones, polyurethanes,polyphenylene-oxides, and thermoplastic polymers like polybutyleneterephthalates and polyethylene terephthalates.

The glass fiber strands that have been used in producing short glass forpolymeric reinforcement are coated by applying a treating or sizingcomposition to the glass fibers as they are formed. This sizingcomposition usually contains a lubricant, a coupling agent, and a filmforming polymer such as poly(vinyl acetate). The selection of thesetypes of components for the sizing component can be crucial to theproperties of the resultant glass fiber reinforced polymer. For example,it is known in the art that the proper selection of a coupling agent hasa significant effect on the properties of resultant reinforcedthermoplastics.

In the production of high performance polymeric materials, in additionto characteristics obtained as a result of the high performanceproperties of the polymer, these materials would be expected to havegood strength properties because of the presence of the glass fibers.For instance, in reinforcing high performance thermoplastic polymers, itwould be expected to achieve a high performance reinforced polymericmaterial with good tensile and impact strength so that the resultantproperties of the high performance polymer can be used mostadvantageously. One such high performance polymer is polycarbonate whichis a polyester of carbonic acid. Glass fibers have been used toreinforce polycarbonate at levels of reinforcement in the range of10-40% glass fibers. It has been reported in Modern Plastics, Volume 43at page 102, that polycarbonate resin reinforced with short glass fiberstrand at a 20% glass content gives a tensile strength at 73° F. (23°C.) of 12,000-18,500 PSI (827-1276 Bars), an elongation at 73° F. (23°C.) of 2.5-3.0%, a flexural strength at 73° F. (23° C.) of 17,000-25,000PSI (1172-1724 Bars), and an Izod impact strength at 73° F. (23° C.) of1.5-2.5 foot pounds/inch (78-134 joule/meter).

It would be advantageous to have glass fiber strands sized with a sizingcomposition that adequately protects the strands from interfilamentabrasion and yields reinforced polymeric resin material with hightensile strength, flexural strength, and impact strength. Such a sizedglass fiber strand would be especially desirable for use in highperformance polymers such as the polycarbonate thermoplastic polymer sothat the high performance properties of the polycarbonate polymer can beutilized most efficiently to achieve high performance properties in themolded reinforced polycarbonate material.

Such achievements can be made while also achieving ease ofprocessability of the glass fibers in producing glass fibers in theirvarious forms and in producing the reinforced polymeric material, suchas by compression molding, injection molding, and the like.

It is an object of the present invention to provide an aqueous sizingcomposition for glass fibers and to provide the sized glass fibers thatyield reinforced polymeric materials having properties such as tensilestrength, flexural strength, and impact strengths at the upper end of orgreater than the range of these strengths as aforedescribed.

SUMMARY OF THE INVENTION

The aforementioned objects and other objects eclectically gleaned fromthe following disclosure and claims are accomplished by the presentinvention.

The present invention is an aqueous sizing composition for treatingglass fibers that yields treated glass fiber strands for producing glassfiber reinforced thermoplastics that have improved physical properties.The aqueous sizing composition has present several specific film formingpolymers, one or more silane coupling agents, and several specific filmformer modifiers where these materials interact to accomplish thedesired objects and goals. The film forming polymers, which must bepresent, include an aqueous dispersible emulsifiable or solubilizablepolyurethane polymer which may be aromatic, aliphatic or alicyclic innature, an aqueous dispersible, emulsifiable or solubilizable1,2-polyepoxide polymer or, in lieu of these two film forming materialsor in addition thereto, an aqueous dispersible, emulsifiable orsolubilizable epoxidized polyurethane copolymer. The aqueous sizingcomposition also has an aqueous dispersible, emulsifiable orsolubilizable polyethylene-containing polymer. The aqueous treatingcomposition also has an aqueous dispersible, emulsifiable orsolubilizable wax and the ratio of the polyethylene-containing polymerto the wax is in the range of about 25:1 to about 1:25. The aqueoustreating compositions also has present one or more silane couplingagents, where one silane coupling agent is an amino silane couplingagent and where other coupling agents present may be a lubricantmodified amino silane coupling agents or one or more epoxy-containingsilane coupling agents.

The aqueous sizing composition is applied to any type of glass fiberknown to those skilled in the art for reinforcing polymeric materials.The application of the sizing composition is performed by any methodknown to those skilled in the art after the molded fibers that arepulled from orifices in a bushing of a glass melting furnace have cooledsufficiently. The sized glass fiber strands can be produced intocontinuous glass fiber strands for subsequent chopping or for continuousstrand reinforcement of polymeric materials, or the sized glass fiberscan be chopped directly during forming, a process known as wet chopping,to produce chopped glass fiber strands for polymeric reinforcement.

The types of polymers in which the sized glass fiber strands can be usedas reinforcement can be any thermoplastic polymeric material known tothose skilled in the art to be reinforceable with glass fibers, althoughthermosetting polymeric materials known to those skilled in the art canalso be used. The sized glass fiber strands have been found mostsuitable for use as reinforcement in thermoplastic polymers and,particularly, the high performance thermoplastic polymers likepolycarbonate and saturated polyesters.

DETAILED DESCRIPTION OF THE INVENTION

It is believed, but the compositions of the present invention are notlimited by this belief, that the accomplishment of obtaining increasedphysical properties in a reinforced polymeric material is achieved withthe use of the aqueous sizing composition of the present invention by aunique blend of components constituting the aqueous sizing composition,where each component contributes needed properties. The film formingmaterials including polyurethane and polyepoxide polymers or copolymersthereof provide a cured and/or evaporative film for the glass fibersand/or strands to assist in holding the filaments together in a bundleof filaments commonly called a strand. In addition, the film formingpolymers have functional groups that assist in bonding the filaments tothe functional end of the silane coupling agent or the thermoplasticpolymer to be reinforced through hydrogen bonding or Van der Wallsforces. The silane coupling agents provide bonding to the glass fibersthrough the hydroxyl groups attached to the silicone atom after thesilane coupling agent has been hydrolyzed, or partially hydrolyzed, andprovide bonding to the matrix polymer to be reinforced or the filmforming polymer through the organic functional group of the silane. Thecombination of the polyethylene-containing polymer and the wax that mayfunction as film former modifiers provide a slip flow characteristic tothe sized glass fiber strands to enable the strands to move relative toeach other in processing and to disperse in the thermoplastic orthermosetting polymer matrix to be reinforced during production of theglass fiber reinforced polymers. This slip flow characteristic of thesized glass fiber strands can be measured by mechanical means such asphysical flow testing, i.e., funnel flow, bulk density levels,rheological spiral flow characteristics and throughput rates duringcompounding. All of these are standard tests known to those skilled inthe art. The film forming polymers must be compatible with the polymericmatrix to be reinforced and must be synergistic with the othercomponents of the aqueous sizing composition. For these reasons, theaqueous dispersible, emulsifiable or solubilizable polyurethane polymeris used in combination with the aqueous dispersible, emulsifiable orsolubilizable polyepoxide polymer.

The polyurethane polymer can be any aqueous dispersible, emulsifiable orsolubilizable polymeric reaction product of a polyol, including glycols,and polyisocyanates including diisocyanates with limited formation ofallophanate and biuret groups. Nonexclusive examples of suitablepolyisocyanates which are employed to produce the polyurethane polymerused with the aqueous sizing composition of the present inventioninclude those having an average NCO functionality of at least about 2,such as, for example, polymethylene polyphenyl isocyanates, suitableorganic diisocyanates, for example, 2,3-toluene-diisocyanate,2,6-toluene-diisocyanate, hexamethylenediisocyanate,P,P'-diphenylmethanediisocyanate, P-phenylenediisocyanate, hydrogenatedmethylene diphenyldiisocyanate (for example, Hylene® W), polyisocyanatenaphthalene diisocyanate, dianisidine diisocyanate, mixtures of one ormore polyisocyanates and the like. Also NCO-containing prepolymers canbe used and these include the reaction products of an excess of anorganic diisocyanate with polyhydroxyl-containing compounds having from2 to about 8 OH groups per molecule such as, for example, ethyleneglycol, glycerine, trimethylolpropane, pentaerylthritol, sorbitol,sucrose, mixtures thereof and/or with dihydroxyl-containing compoundsuch that the average hydroxyl functionality in the mixture is at leastabout 2.0. It is preferred that these polyurethanes are liquid, however,in the event that they are solids or semisolids or of a relatively highviscosity such that blending with the other components would bedifficult or inconvenient, they may be prepared in a suitable solvent orby melting and then emulsified into an oil-in-water emulsion withsuitable surfactants. Nonexclusive examples of suitable polyol ordihydroxyl-containing compounds which may be used in forming thepolyurethane include, ethylene glycol, propylene glycol, butyleneglycol, pentanediol, hexanediol, diethyleneglycol, dipropylene glycol,bisphenol A, resorcinol, catechol, hydroquinone, mixtures thereof,adducts of a dihydroxyl-containing compound and a viscinal epoxycompound such as, for example, ethyleneoxide, 1,2-propylene oxide,1,2-butyleneoxide, epichlorohydrin, epibromohydrin, mixtures thereof andthe like. When the dihydroxyl-containing compound is a solid, it issuitably employed by either dissolving it in a suitable solvent ormelting it and then converting it into an oil-in-water emulsion by useof suitable surfactants and water.

Of this class of polyurethanes, curable, blocked, polyurethane polymerscan be used which are aromatic, aliphatic or alicyclic in nature. Theemulsions or dispersions are formed by dissolving the polyurethaneprepolymer in a nonreactive organic solvent for the polyurethane in asufficient amount, for example 20-50 percent by weight based upon theweight of the solution, adding sufficient surfactants with the properHLB range and then gradually mixing the solution with sufficient waterto form a stable emulsion of droplets of the solution in the water.These blocked polyurethane resins are formed by the reaction of apolyisocyanate, such as toluene diisocyanate adducts of hydroxylterminated polyether or polyester resins with an end blocking compoundcontaining active hydrogen atoms such as an amide or polyamide accordingto conventional techniques for the production of polyurethane resins.The polyisocyanate can be referred to as a prepolymer, i.e., an adductof a simple diisocyanate with a suitable polyfunctional resin.Particularly suitable polyurethane polymers are those that aresubstantially aliphatic or alicyclic in nature where the majority of thepolyurethane polymeric chain is constituted of aliphatic or hydrogenatedaromatic, or alicyclic moieties. Particularly suitable aqueous emulsionsof polyurethane polymers are designated "Rucothane®" latices designatedas 2010L, 2020L, 2030L, 2040L, 2050L, and 2060L. These materials areavailable from the Ruco Division of Hooker Chemical Corporation, NewYork. These materials are thermoplastic urethane latices having avarying particle size of a high molecular weight aliphatic isocyanatebased thermoplastic elastomer in a water dispersion with an anionic ornonionic surfactant. The most preferred polyurethane used is one that isa carboxylated polyurethane to assist in water dispersibility. TheRucothane latices are based on aliphatic components and have a polymersolids content in stable emulsions ranging from 55-65% by weight. TheRucothane latices have a Brookfield viscosity RVF4 in centipoise at 2RPM ranging from 7,000 for about 2060L and 2030L latices up to 25,000for the 2020L latex. Another nonexclusive example of a polyurethanepolymer that can be prepared is one that is formed from the aliphatic oralicyclic isocyanate available from E. I. DuPont de Nemours and Co.under the trade designation "Hylene W". The amount of the polyurethanepolymer used in the aqueous sizing composition is in the range of about1 to about 10 weight percent of the aqueous sizing composition and about20 to about 60 weight percent of the solids of the aqueous sizingcomposition.

A suitable epoxy compound for use in the aqueous sizing of the presentinvention is one that contains more than one group which has an oxygenatom attached to adjacent carbon atoms, known as an oxirane ring anddepicted by the formula ##STR1## It is well known that epoxy resins maybe prepared as a reaction product of a halohydrin and a phenol. Onegroup of polyepoxy compounds which may be used is obtained by thereaction of a stoichiometric excess of an epihalohydrin, such as anepichlorohydrin, with a polyhydric phenol such as bis-(4-hydroxyphenyl)-2,2-propane, bis(hyroxy phenyl) methane (obtained by the acidcondensation of two moles of phenol with one mole of formaldehyde),hydroquinone, resorcinol, etc., or with a polyhydroxy alcohol such asglycol, polyethylene glycol, sorbitol, glycerol, etc. The epoxy resinhas an epoxy equivalent weight of about 170 to about 900. By varying theproportions of the epihalohydrin and the phenolic polyhydroxic compoundsand/or by varying the reaction conditions, compounds of varying epoxideequivalents within this range can be produced which range from liquid tosolid, but are preferably liquid. Typically, the molecular weight rangecan be between about 300 to about 900, and more preferably between about300 and 600. The epoxy resin or resins can be used in an amount of about0.1 to about 10 weight percent of the aqueous sizing composition andpreferably about 0.2 to about 3.5 percent by weight based on the totalweight of the aqueous sizing composition. A particularly suitable epoxyresin for use in the sizing composition of the present invention isdesignated "Epi-rez CMD 35201" commercially available from CelanesePolymer Specialties Co. This epoxy resin is an epoxy resin dispersionwhich has 59% nonvolatiles with the only volatile being water and aweight per epoxide of approximately 530, a pH of 8.3 and an averageparticle size between 1 and 4 microns. This epoxy resin may be curedusing any conventional epoxy curing agents with allowance being made forthe water environment. Another suitable epoxy resin that can be used isdesignated "Genepoxy 370-H55" which is commercially available fromGeneral Mills Chemical Division.

The copolymers of epoxy and polyurethane, which can be used in thepresent invention are those formed by use of a polyepoxide prepolymerhaving one or more oxirane rings and also having open oxirane rings,which are used as the hydroxyl groups for the dihydroxyl-containingcompounds for reaction with diisocyanates or polyisocyanates. The amountof an epoxidized polyurethane copolymer used in the aqueous sizingcomposition would range from about one to about 20 weight percent of theaqueous sizing composition. When the polyurethane polymer and epoxypolymer are used separately in the aqueous sizing composition, anyamount in the aforementioned ranges can be used, but the weight ratio ofthe polyurethane polymer to the epoxy polymer should be in the range ofabout 90 to 10 to about 10 to 90 and preferably in the range of about5:1 to about 1:5 with the most preferred range being about 1:1 to about3:1.

The aqueous dispersible, emulsifiable or solubilizablepolyethylene-containing polymer useful in the aqueous sizing compositionof the present invention is a polymer that contains predominantlypolyethylene but which may also contain a minor portion of polypropyleneor degradation derivatives thereof. The aqueous solubilizable ordispersible polyethylene employed in the aqueous sizing composition canbe a low density, medium density, or ultra-high molecular weightpolyethylene, or thermal or oxidative degradation derivatives thereof.The polyethylenes can be produced by any conventional processes, forexample, the high pressure polymerization process, Ziegler process,Phillips process, Standard Oil Process and the like. The thermaloxidation can be conducted by any method known to those skilled in theart and the oxidative degradation can be performed with anyoxygen-containing gas like oxygen and/or ozone. The low densitypolyethylene has highly branched and highly spaced chains, whereas thehigh density polyethylene and ultra-high molecular weight polyethyleneare substantially linear and have closely aligned chains. The branchchained, low density type polyethylene has a specific gravity of around0.915, crystallinity of 50-60% and it is derived from ethylene which ispolymerized in a free radical-initiated liquid phase reaction atelevated pressure and temperature with the use of catalysts. The highdensity polyethylene has a specific gravity of around 0.95,crystallinity of 90% and is polymerized from ethylene by the use ofZiegler or supported metal oxide catalysts at from one to 100atmosphere, at from room temperature to 200° F. ( 93° C.). The ethylenemay be copolymerized with varying percentages of 1-olefins or othermaterials, for example, 1-pentene, 1-butene and the like and 2-butene oracrylic acid and propylene from which a crystalline product results.When the polyethylene is a copolymer of polyethylene and polypropylenewith a majority of the copolymer being polyethylene, the polypropylenethat is employed has an average molecular weight in the range of about5,300 to 7,300 and a ring and ball softening point of 150° to 175° C., adensity of 0.85 to 1 gram per cubic centimeter and a penetrationhardness (100 grams/5 seconds/72° F.) in tenths of a millimeter of 0.01maximum. The average molecular weight of the starting polyethylene is inthe range of about 2,000 to greater than 1.5 million.

When the higher molecular weight polyethylene can not be dispersed,emulsified or solubilized in water by standard techniques, thepolyethylene can be degraded by heat or oxidation to reduce themolecular weight. Such standard techniques include emulsifying thepolyethylene or polyethylene polypropylene copolymer by melting thepolyethylene or polyethylene polypropylene copolymer and adding suitableemulsifying agents. This mixture is stirred and then water is addeduntil the water and oil emulsion inverts to an oil-in-water emulsion.The emulsion contains about 15 to about 40% by weight of solids(non-aqueous ingredients) based upon the weight of the emulsion.Suitable emulsifying agents include Triton X100 surfactants, IgepalCO630 surfactant and Tergitol surfactants and various anionicemulsifying agents. A polyethylene emulsion which is suitable for use inthe practice of the present invention is commercially available underthe trade designation "Protolube HD" from Proctor Chemical Co., Inc.This material is a nonionic polyethylene emulsion having a solidscontent of approximately 26%, a pH (1% solution) of approximately 8 andwith approximately 75% water which has an appearance of a milky emulsionand an odor of a mild wax.

When the polyethylene is degraded to reduce the molecular weight inorder to retain an aqueous dispersible, emulsifiable or solubilizablepolyethylene, it is preferred that the degradation occur by a methodthat reduces the formation of branching and of double bonds in thedegraded product. Such a method is to thermally degrade the polyethyleneand then oxidatively degrade the polyethylene with a mixture of oxygenand ozone in the presence of low molecular weight polyethylene as shownin U.S. Pat. No. 3,692,877.

The amount of the aqueous dispersible, emulsifiable or solubilizablepolyethylene-containing polymer used in the aqueous sizing compositionranges from about 0.1 to about 7 weight percent of the aqueous sizingcomposition and preferably about 0.1 to about 3 weight percent of theaqueous sizing composition. The amount of the polyethylene-containingpolymer on a solids basis in the sizing composition is from around 1 toabout 25 weight percent of the solids of the sizing composition.

In addition, the aqueous sizing composition of the present invention hasan aqueous soluble, emulsifiable or dispersible wax. The wax may be anysuitable wax selected from the group consisting of vegetable waxes, suchas carnauba, Japan, bayberry, candelilla, and the like; animal waxessuch as beeswax, Chinese wax, hydrogenated sperm oil wax and the like;mineral waxes such as ozocerite, montan, ceresin and the like; andsynthetic waxes such as polyalkylenes like polyethylenes, polyethyleneglycols, polyethylene esters, chloronaphthalenes, sorbitals;polychlorotrifluoroethylenes; petroleum waxes such as paraffin,microcrystalline waxes and the like. The waxes are preferably thosehaving a high degree of crystallinity and obtained from a paraffinicsource, and most preferably are microcrystalline waxes. Themicrocrystalline waxes usually are branched chain paraffins having acrystal structure much smaller than that of normal wax and also a muchhigher viscosity and they are obtained by dewaxing tank bottoms,refinery residues and other petroleum waste products. Of these waxes,the most preferred is that having a melting point of about 50° C. ormore. The waxes are typically used in the sizing formulation of theinstant invention as aqueous dispersions containing 20 to 60 percent byweight wax. In the aqueous sizing formulation of the present inventionthe wax component is present in an amount of about 0.01 to about 6 andpreferably 0.01 to 2 weight percent of the aqueous sizing composition.On a solids basis of the sizing composition, the aqueous dispersible waxis present in an amount of about 0.1 to about 10 preferably about 0.1 toabout 4 weight percent. An example of a suitable wax material is thatavailable from Boler Petroleum Co. under the trade designation "518Emulsion". This material is a thixotropic anionic microcrystalline waxemulsion with a melting point of around 87° C. to 92° C. and a percentsolids of around 30±0.5 determined by azotropic distillation and aviscosity at 21° C. of 61±5 centipoise measured according to LVFBrookfield, No. 2 spindle at 60 RPM for 2 minutes, and with a pH at 21°C. of 8.5. Another example of a wax dispersion useful in thecompositions of the present invention is that as designated 84630available from Michelman Chemical Co.

When the polyethylene-containing polymer that is used in the compositionof the present invention has a limited amount of branching such aspolyethylene with a density greater than around 0.935, the amount of waxpresent in the composition can be deleted or reduced. The amount of waxcan range from 0 to about 2 weight percent of the aqueous sizingcomposition or from 0 to about 4 weight percent of the solids of theaqueous sizing composition. The polyethylene with limited branching isan aqueous dispersible, emulsifiable, or solubilizable medium density,high density or ultra-high molecular weight polyethylene or adegradation derivative thereof prepared by thermal or oxidativedegradation in such a manner as to limit the formation of double bondsand branching in the polymer chain. By limited branching, it is meantthat the polydispersity index (Mw/Mn) is less than 10 and preferablyless than 3. The polyethylene with limited branching may also containsmall amounts of methyl groups on and/or carbon double bonds in thepolymer chains.

The aforementioned components of the aqueous sizing compositionincluding the polyurethane, epoxy or epoxypolyurethane copolymerfunction generally in the sizing composition as film formers. Thepolyethylene-containing polymer and wax function generally as filmformer modifiers. These materials generally function to provide a filmcoating to protect the fibers. In particular, the polyurethane filmformer provides compatability with the matrix resin in addition toproviding film forming characteristics for the strand. The polyepoxidepolymer with the intermediate molecular weight range, small averageparticle size, and good shear stability can also be crosslinked withepoxy hardener to make the film coating less soluble in organicenvironments as demonstrated by acetone extraction. This polyepoxidealso functions as a film forming polymer for the strand but, inaddition, provides compatability with the thermoplastic matrix to bereinforced. In addition, these materials also provide functional groupswhich can provide, by hydrogen bonding or by Van der Wall forces,chemical bonding with the thermoplastic matrix and the glass fiberstrand or silane compounds bonded to the glass fiber strands. Thepolyethylene-containing polymer in conjunction with the wax modifies thefilm forming characteristic and serves as processing aids whichcontribute to higher impact strength for the reinforced thermoplasticmaterial. This processing assistance is providing the sized glass fiberstrands with a slip/flow characteristic. To achieve this characteristic,the weight ratio of the polyethylene-containing polymer to the wax mustbe in the range of about 25:1 to about 1:25. A slightly lesser degree ofslip flow characteristic can be provided by just the presence of apolyethylene polymer with limited crosslinking. The slip/flowcharacteristic is measured by a funnel flow test. This test is conductedby placing a predetermined weight of chopped glass fiber strand in afunnel equipped for vibration. The time it takes for the predeterminedweight to pass through the vibrating funnel is the funnel flow time.This time can range from several seconds for good slip flowcharacteristics to several minutes for poorer slip flow characteristics.

The aqueous sizing composition also has one or more silane couplingagents, where at least one silane coupling agent is an amino silanecoupling agent. The amino silane coupling agent can be selected from thegroup of monoamino and diamino silanes. In addition to the amine silanecoupling agent, there may be present an amino silane coupling agentmodified with any known textile lubricant. Both of these silane couplingagents, when they are monoamino silane coupling agents would have aminofunctionality which can be designated by the general formula

    NH.sub.2 R-Si-(OR.sup.1).sub.3

wherein: R is an alkylene radical having from 2 to 8 carbon atoms and R¹is a lower alkyl radical or hydrogen; the lower alkyl radical having 1to 5 carbon atoms, preferably having 1 or 2 carbon atoms.

Nonexclusive examples of amino silanes includegamma-aminopropyltriethoxysilane, N-(trimethoxy silylpropyl)ethanediamine acrylamide, aminomethyltriethoxysilane,aminopropyltrimethoxysilane, diaminopropyldiethoxysilane,triaminopropylethoxysilane, other similar mono and diamino silanes. Inaddition to the amino silane, there may be present an epoxy-containingsilane coupling agent having a formula such as ##STR2## Where R¹ is asdescribed above and Y is an integer from 1 to 6. Representative examplesof the epoxy silanes include beta-hydroxyethyltriethoxysilane;gamma-hydroxypropyltrichlorosilane;bis-(delta-hydroxybutyl)dimethoxysilane;deltahydroxybutyltrimethoxysilane; 2,3-epoxypropyltrimethoxysilane;3,4-epoxybutyltriethoxysilane; bis-(2,3-epoxypropyl)dimethoxysilane;glycidoxypropyltrimethoxysilane; and,3,4-epoxycyclohexyltriethoxysilane. A number of other silanes containingat least one organic group substituted by one or more of an amino groupor epoxy group may also be used in the practice of the presentinvention, and these silanes are well known to those skilled in the art.

As will be appreciated by those skilled in the art, the aforementionedsilane coupling agents can be used as the silane coupling agent or itsfully or partially hydrolyzed products (silanols) or its polymerizationproduct (polysiloxane). The amount of the silane coupling agent presentin the aqueous sizing composition is in the range of about 0.1 to about2 weight percent of the aqueous sizing composition.

It is preferred to use a mixture of the silane coupling agents whichcontains the amino silane in a predominant amount of the 0.1 to 2 weightpercent of the aqueous sizing composition, and a minor amount of thelubricant modified amino silane coupling agent. The most preferredmixture of the silane coupling agents used in the aqueous sizingcomposition of the present invention utilizes the amino silane in thepredominant amount, the epoxy silane in a minor amount and the lubricantmodified amino silane in a smallest amount of the 0.1 to 2 weightpercent of the aqueous sizing composition. This mixture of silanecoupling agents has in weight percent of the mixture 50 to 95 weightpercent of an amino silane coupling agent, about 5 to about 50 weightpercent of an epoxy silane coupling agent and about 1 to about 10 weightpercent of a lubricant modified amino silane coupling agent.

As can be appreciated by those skilled in the art, additionalingredients can be included in the aqueous sizing composition such asadditional film formers, lubricants, wetting agents, surface energymodifiers such as surfactants for facilitating sizing stability,coatability, uniformity, and wettability, and process aids to promotemechanical handling properties during the fabrication and use ofresultant sized chopped glass fiber strand product. These agents aregenerally known to those skilled in the art.

The total solids (non-aqueous) content of the sizing composition isabout 1 to about 30% by weight of the size, and it is preferably about 3to about 10% by weight of the size. In all events, the amounts of thesolid components of the aqueous sizing composition should not exceedthat amount which will cause the viscosity of the solution to be greaterthan about 100 centipoise at 20° C. Solutions having a viscosity ofgreater than 100 centipoise at 20° C. are very difficult to apply toglass fiber strands during their formation without breaking the strand.It is preferred that the viscosity of the size be between 1 and 20centipoise at 20° C. for best results. The pH of the aqueous sizingcomposition can be varied from about 4 to about 9.

The aqueous sizing composition is applied to the fibers to obtain asolids application of generally about 0.1 to about 3% by weight based onthe total weight of the fibers and the sizing composition, and morepreferably between about 0.5 and 2% by weight. The aqueous sizingcomposition is applied to the glass fibers during the conventionalforming process to produce sized continuous glass fiber strands or wetchopped glass fiber strands. In producing continuous glass fiberstrands, the sizing composition is applied generally to the fibers priorto the time they are gathered together to form one or more strands bymeans of any applicator known in the art to contact a liquid with asolid substrate. An example is a roller applicator, which is partiallysubmerged in the sizing composition, contained in a reservoir such asthe applicator shown in U.S. Pat. No. 2,728,972, hereby incorporated byreference, while other examples are spray applicators and padapplicators.

The sized glass fibers are gathered into strands by a gathering shoe andwound onto a forming package rotating at a sufficient speed to attenuatethe fibers from the orifices in a bushing of a glass fiber batch meltingfurnace. Although one or more strands may be formed by means other thanwinding on a forming tube, such as by means of a pair of rotating wheelpullers which direct fibers into a suitable collecting device. Anexample of such a process is the production of wet chopped glass fiberstrands. In this process the glass fibers are drawn from cones of moltenglass by attenuation and sized with the aqueous sizing composition. Theattenuation is provided by a pair of rotating circumferentially juxposedwheels. As the glass fibers are attenuated by these two wheels, they arealso cut or chopped as is more fully explained in U.S. Pat. No.3,869,268, hereby incorporated by reference. As can be appreciated bythose skilled in the art, any conventional method for producing wetchopped glass fiber strands or dry chopped glass fiber strands duringthe forming process for producing glass fibers can utilize the aqueoussizing composition of the present invention.

When the glass fiber strands are formed by a wet chop glass fiberforming process, and dried in a drier with a high temperature of around150° C. or higher, and a short residence time of around a second to afew minutes, it is preferred that the aqueous sizing composition used totreat the glass fiber strands contain the mixture of amino silane andepoxy silane coupling agents. The mixture of these silane couplingagents is used in order to achieve good impact properties for thesubsequently reinforced thermoplastic polymer even with the rapid dryingof the glass fiber strands during their formation. When the glass fiberstrands are processed into continuous glass fiber strands, they aredried in conventional drying ovens at the preferred conditions oftemperatures around 110° C. to around 150° C. for around 11 hours. Othertime/temperature relationships can be used as long as they giveequivalent drying to remove a substantial amount of moisture and set thecure of the sizing composition as a coating. After this drying step, thecontinuous glass fiber strands can be chopped or processed into rovingor any other desired construction for reinforcement of thermoplastic orthermosetting polymers.

In preparing reinforced thermoplastic materials, the thermoplasticpolymers that can be reinforced with the sized glass fiber strands ofthe present invention can be any thermoplastic polymer, but the polarthermoplastic polymers are preferably used. Nonexclusive examples ofthese include polyamides, polyphenylsulfides, polycarbonates,polyolefins, polystyrene, acetal resins, and styrene acrylonitrilecopolymers and terpolymers with butadiene. The sized glass fiber strandscan be combined with the thermoplastic polymer to be reinforced by anyconventional method known to those skilled in the art. Any mixingapparatus generally used by those skilled in the art for producingreinforced thermoplastic polymers can be utilized. The chopped sizedglass fiber strands can be compounded with the thermoplastic polymer andmolded by any conventional molding process such as injection molding,rotational molding, compression and extrusion molding. Generally, ininjection molding a standard plunger or screw injection-moldingapparatus can be used. When the sized glass fiber strands arecontinuous, continuous glass fiber strand mats can be formed and used incompression molding of the thermoplastic material. The amount of glassfiber strands combined with the thermoplastic polymer can range fromaround 1 weight percent of the reinforced thermoplastic polymer toaround 50 percent by weight.

PREFERRED EMBODIMENT

In the preferred embodiment of the present invention, the aqueous sizingcomposition is formulated and used to treat glass fibers that are formedinto wet chopped glass fiber strand for reinforcement of polycarbonate.The aqueous sizing composition has the following formulation:

    ______________________________________                                                           Amount in  Amount in                                                          Solid      Aqueous                                         Component          Weight %   Weight %                                        ______________________________________                                        (1)  Water for numbers (2)                                                                           10-50 percent                                                                            10-50 percent                                    and (3)           of total   of total                                                           volume     volume                                      (2)  Gamma amino       2 to 7     .05 to 1                                         propyltriethoxy-                                                              silane (A-1100)                                                          (3)  Lubricant modified                                                                              .05 to 1   .005 to 1                                        gamma aminopropyl-                                                            triethoxysilane (A-1108)                                                 (4)  Acetic acid to adjust                                                         pH to 7.5 ± 1.0                                                       (5)  Gamma glycidoxy-  0.5 to 3   0.05 to 1                                        propyltrimethoxy-                                                             silane (A-187)                                                           (6)  Cold water for    1 to 60 liters                                              the gamma-glycidoxy-                                                          propyltrimethoxy-                                                             silane                                                                   (7)  Substantially     5 to 60    1 to 5                                           aliphatic poly-                                                               urethane polymer                                                              with a small                                                                  amount of carboxyla-                                                          tion (Rucothane 2010L)                                                   (8)  Polyethylene containing                                                                         5 to 20    0.1 to 3                                         polymer (aqueous emulsion                                                     available as Protolube HD)                                               (9)  Epoxy polymer (aqueous                                                                          5 to 60    1 to 5                                           dispersion available as                                                       CMD 35201)                                                               (10) Microcrystalline wax                                                                            .5 to 3    0.01 to 1                                        with a melting point                                                          greater than 70° C.                                                    (available as Boler 518                                                       Wax Emulsion)                                                            ______________________________________                                    

The aforementioned formulation was prepared into a sizing composition byfirst adding deionized water to a mix tank having stirring capabilities.The amount of water added to the mix tank is around 10 to 50 percent ofthe total volume of the sizing composition. Thegamma-amino-propyltriethoxysilane available as A1100 from Union CarbideCorporation was added to the mix tank with agitation for severalminutes. The lubricant modified gamma-aminotriethoxysilane availablefrom Union Carbide under the trade designation A-1108 which was added tothe mix tank and agitated for several minutes. The pH was adjusted toaround 6.5 to 8.5 with diluted (50/50) acetic acid. A small amount ofwater was added to a premix tank and thegamma-glycidoxypropyltrimethoxysilane available from Union CarbideCorporation under the trade designation A187 was added to the premixtank and the mixture was then added to the main mix tank. The main mixtank at this point contained a mixture of the silane coupling agents tobe used in the aqueous sizing composition. The polyurethane polymerwhich is substantially aliphatic or alicyclic, is available from HookerChemical Company under the trade designation Rucothane aqueous emulsion.The polyethylene-containing polymer which is a high density polyethyleneemulsified into an aqueous emulsion available from Proctor ChemicalCompany under the trade designation Protolube HD is added to the mainmix tank. The polyepoxide polymer as an aqueous solution available fromCelanese Specialties Chemical Company under the trade designationCMD35201 having a weight per epoxide of around 530 was added to the mainmix tank. The microcrystalline wax available as an emulsion designated"Emulsion 518" with a melting point in the range of about 85° to about95° was added the the main mix tank. The mixture in the main mix tankwas then diluted to the final desired volume and allowed to agitate forseveral minutes.

The aqueous sizing composition was used to treat glass fibers having afilament diameter of 13.34±0.63 microns gathered into strands having 500to 1000 filaments per strand and chopped during formation into choppedglass fiber strand having lengths ranging from 1/8" to 1/4 inch. The LOI(Loss On Ignition) of the chopped strand ranged from 0.6 to 1.25percent. This chopped glass fiber strand was used in injection moldingto reinforce polycarbonate resin.

Additional examples of carrying out the invention are shown in thefollowing examples of the aqueous sizing compositions.

Table I presents five examples of aqueous sizing compositions. All theaqueous sizing compositions were formulated as taught in the preferredembodiment.

Examples 1 and 2 were used to prepare continuous sized glass fiberstrands which were subsequently chopped for reinforcing polycarbonateresin. The sizing compositions of Examples 3, 4, and 5 were applied toglass fibers produced into wet chopped glass fiber strand andsubsequently used to reinforce polycarbonate resin. Table II presentsdata showing physical properties of reinforced polycarbonate polymer.The polycarbonate resin was reinforced with the glass content depictedin Table II by extrusion molding into placques.

                                      TABLE I                                     __________________________________________________________________________                     Example 1                                                                           Example 2                                                                           Example 3                                                                           Example 4                                                                           Example 5                            __________________________________________________________________________     Total Volume    189.25 liters                                                                       189.25 liters                                                                       189.25 liters                                                                       378.5 liters                                                                        189.25 liters                        Components - kilograms                                                        Gamma-glycidoxy-propyl-                                                                        --    0.5   --    1.0   --                                   trimethoxy-silane A-187                                                       Water            --    --    --    45.4 liters                                                                         --                                   Gamma-aminopropyl-                                                                             1.0   0.5   1.0   3.3   0.2                                  triethoxy silane A-1100                                                       Lubricant modified                                                                             .04   0.4   0.4   0.18  0.008                                gamma-aminopropyl-                                                            triethoxy silane (A-1108)                                                     Acetic Acid, pH adjustment                                                                     0.29  0.29  0.29  1.01  0.04                                 Polyurethane emulsion (2010L)                                                                  10.0  10    10    26.6  2.0                                  Polyethylene emulsion                                                                          5     10    10    13.3  2.0                                  (Protolube HD)                                                                Microcrystalline Wax m.p.                                                                      0.6   0.6   0.6   1.6   0.12                                 87-92° C. (Boler 518)                                                  Epoxy polymer emulsion A                                                                       10.0  10.0  10    26.6  2.0                                  (CMD 35201)                                                                   Percent Solids   7.25  8.03  7.9   10.4 ± 0.6                                                                       9.8                                  Sized Chopped Glass Fiber Strand                                              Type of Glass Fiber Strand                                                                     K-37  K-37  K-6.75                                                                              K-6.75                                                                              K-6.75                               LOI (%)          1.13  1.29  .7    0.75  .75                                  Bulk density     34    34.9  35.3  43    37                                   lb/ft.sup.3                                                                   Funnel Flow, sec./1 kg.                                                                        4     5.5   5     4.5   5                                    Strand Integrity for Chopping                                                                  Excellent                                                                           Excellent                                                                           Excellent                                                                           Excellent                                                                           Excellent                            __________________________________________________________________________

The funnel flow test was conducted by placing a given quantity of thechopped glass fiber strands either dry chopped or dried wet chop in afunnel equipped for vibration. The time it took the total weight to passthrough the funnel was recorded.

The bulk density test measures slip flow characteristic in relation tocompaction of chopped glass fiber strands. Compaction comes into play inmolding reinforced thermoplastic polymeric materials. Bulk density ismeasured by filling a test tube with known volume with chopped glassfiber strands. The test tube is placed on a shaker and the volumeoccupied by the strands after shaking is recorded. Higher volumesindicate better bulk density.

In Table II, tensile strength, flexural strength, flexural modulus andIzod impact tests were conducted according to test methods of theAmerican Society of Testing and Materials (ASTM). These tests includedrespectively D-638, D-790, D-790 and D-256.

                                      TABLE II                                    __________________________________________________________________________    PROPERTIES OF POLYCARBONATE.sup.1 REINFORCED WITH                             GLASS FIBER STRAND PRODUCED AS SHOWN                                          IN TABLE I                                                                                                                 Flexural                                                                      Modulus    Izod                                  Glass                                                                              Tensile Strength                                                                          Flexural Strength                                                                         PSI × 10.sup.6                                                                     Impact                                Content                                                                            PSI × 10.sup.3                                                                      PSI × 10.sup.3                                                                      (Grams per cm..sup.2                                                                     Ft/lb/In              Glass Fiber Strand                                                                            %    (Grams per cm..sup.2 × 10.sup.3)                                                    (Grams per cm..sup.2 × 10)                                                          10.sup.6)  (Joules/cm)           __________________________________________________________________________    ASTM Test Method     D-638       D-790       D-790      D-256                   Published Short fiber                                                                       20   12-18.5     17-25       --         1.5-2.5                                    (843.6-1300.6)                                                                            (1195.1-1757.5)        (105.5-175.8)           1/4 inch K-37 with                                                                          20   19.1        26.8        0.901      2.78                    size of Example 1  (1342.7)    (1884.0)    (63.3)     (195.4)                 1/4 inch K-37 with                                                                          20   19.4        27.2        0.907      2.85                    size of Example 3  (1363.8)    (1912.2)    (63.8)     (200.4)                 1/4 inch M fibers 4.8                                                                       20   17.4        25.2        0.859      2.57                    with size of Example 4                                                                           (1223.2)    (1771.6)    (60.4)     (180.7)                 1/4 inch K-37 with                                                                          34.5 18.7        25.6        1.0        1.97                    size of Example 1  (1314.6)    (1799.7)    (70.3)     (138.5)                 1/8 inch K-37 with                                                                          33.9 18.2        24          1.0        2.04                    size of Example 1  (1279.5)    (1687.2)    (70.3)     (143.4)                 1/4 inch K-37 with                                                                          31.9 21.0        28.4        1.04       2.9                     size of Example 2  (1476.3)    (1996.5)    (73.1)     (203.9)                 1/8 inch K-37 with                                                                          32.3 20.1        28.7        1.0        3.0                     size of Example 2  (1413.0)    (2017.6)    (70.3)     (210.9)                 1/4 inch K-6.75 with                                                                        30   18.3        26          1.06       2.61                    size of Example 4  (1286.5)    (1827.8)    (74.5)     (183.5)                 formed by wet chop process                                                  10.                                                                             1/8 inch K-6.75 with                                                                        35   18.4        24          .95        2.41                    size of Example 4  (1293.5)    (1687.2)    (66.8)     (169.4)                 formed by wet chop process                                                    1/4 inch M-4.8 with                                                                         20   16.4        25.4        0.94       2.3                     size of Example 4  (1152.9)    (1785.6)    (66.1)     (161.7)               __________________________________________________________________________     .sup.1 Polycarbonate resin was LEXAN141-111 polycarbonate from General        Electric.                                                                

As is shown in the data of Tables I and II, the sized glass fiberstrands of the present invention lead to high integrity chopped strandproducts that also have good slip/flow characteristics. The epoxypolymer contributes to the high abrasion resistence of the strands,while the polyurethane and film former modifiers,polyethylene-containing polymer and wax contribute to the high impactproperties in the resultant glass fiber reinforced thermoplasticpolymer.

The foregoing has described an aqueous sizing composition and sizedglass fiber strand made therefrom that can be used in reinforcingthermoplastic polymers to yield reinforced thermoplastics with higherstrength properties. This result is obtained from the components in theaqueous sizing composition which include a polyurethane polymer, anepoxy polymer, a polyethylene-containing polymer, a wax, an amino silanealone or in combination with a lubricant modified amino silane and/or anepoxy containing silane coupling agent. The aqueous sizing compositionis applied to glass fibers for production of wet chopped glass fiberstrand or dry chopped glass fiber strand. The chopped glass fiber strandcan then be blended with the thermoplastic polymer and molded into thedesired shape.

We claim:
 1. An aqueous sizing composition for glass fibers used forreinforcing polymers, comprising:a. a polyurethane polymer, b. a epoxypolymer, c. a polyethylene-containing polymer, d. wax where the weightratio of the polyethylene-containing polymer to wax is in the range ofabout 25 to 1 to about 1 to 25, and e. an amino silane coupling agent,and f. water in an amount to give a total solids content for thecomposition in the range of about 1 to about 30 weight percent. 2.Aqueous sizing composition of claim 1 wherein the polyurethane polymeris substantially aliphatic and/or alicyclic.
 3. Aqueous sizingcomposition of claim 1 which includes a lubricant modified amino silanecoupling agent.
 4. Aqueous sizing composition of claim 1 which includesan epoxy containing silane coupling agent.
 5. Aqueous sizing compositionaccording to claim 1 wherein the polyurethane and epoxy polymers arepresent as an epoxidized polyurethane copolymer.
 6. Aqueous sizingcomposition of claim 1 wherein the polyurethane polymer hascarboxylation.
 7. Epoxy polymer of claim 1 that has a molecular weightin the range of about 170 to 900 (number average or weight average). 8.Aqueous sizing composition of claim 1 wherein thepolyethylene-containing polymer is selected from high densitypolyethylene, medium density polyethylene, low density polyethylene,ultra-high molecular weight polyethylene, polyethylene-1-olefincopolymers and polyethylene, polypropylene copolymer where polyethyleneis present in the major amount in the copolymers and degradationderivatives thereof.
 9. Aqueous sizing composition of claim 1 whereinthe wax has a melting point above about 50° C.
 10. Aqueous sizingcomposition of claim 1 wherein the amino silane isgamma-aminopropyltriethoxy silane.
 11. Aqueous sizing composition ofclaim 1 wherein the lubricant modified amino silane coupling agent isgamma-aminopropyltriethoxy silane.
 12. Aqueous sizing composition ofclaim 1 wherein the epoxy-containing silane isgamma-glycidylpropyltrimethoxysilane.
 13. Sized glass fiber strandcontaining the aqueous sizing composition of claim
 1. 14. Dried choppedglass fiber strands having an LOI in the range of about 0.1 to 3 of thesizing composition of claim
 1. 15. Wet chopped glass fiber strandshaving the aqueous sizing composition of claim
 1. 16. Reinforcedthermoplastic polymer having the sized glass fibers of claim 14 or 15.17. Reinforced thermoplastic polymer of claim 16 wherein thethermoplastic polymer is selected from polypropylene; polyamide;saturated polyesters including polyethylene terephthalate andpolybutylene terephthalate; polystyrene; phenoxy polyphenylene oxide;polyphenylene sulfide; polycarbonate, andacrylonitrile-butadiene-styrene terpolymer.
 18. Aqueous sizingcomposition for glass fibers used to reinforce thermoplastic polymers,comprising:a. aqueous dispersion of substantially aliphatic and/oralicyclic polyurethane polymer, b. aqueous dispersion of 1,2-polyepoxidepolymer with a molecular weight in the range of 170 to 900, where theweight ratio of polyurethane to epoxy is in the range of about 1 toabout 10 to about 10 to about 1, c. aqueous dispersion ofpolyethylene-containing polymers selected from the group consisting oflow density polyethylene, medium density polyethylene, high densitypolyethylene, ultra-high molecular weight polyethylene andpolyethylene-polypropylene copolymer and polyethylene-1-olefin copolymerwhere polyethylene is present in a predominant amount of the copolymerand degradation derivatives thereof, d. paraffin wax with a meltingpoint greater than 50° C., e. mixture of silane coupling agents havingin weight percent of the mixture: 50 to about 95 weight percent of anamino silane coupling agent, about 5 to about 50 weight percent of anepoxy silane coupling agent and about 1 to about 10 weight percent of alubricant modified amino silane coupling agent. f. water in an amount togive a total solids for the composition in the range of about 1 to about30 weight percent.
 19. Aqueous sizing composition according to claim 18wherein the polyurethane polymer contains carboxyl moieties.
 20. Aqueoussizing composition of claim 18, wherein the epoxy polymer has a weightper epoxide of around
 530. 21. Aqueous sizing composition of claim 18wherein the amino silane is gamma-aminopropyltriethoxy silane and theepoxy silane is gamma-glycidoxy propyltrimethoxy silane.
 22. Choppedglass fiber strand having the dried residue of the aqueous sizingcomposition of claim
 18. 23. Chopped glass fiber strand having theaqueous sizing composition of claim
 18. 24. Thermoplastic polymerreinforced with the glass fiber strands of claim 22 or 23 wherein thethermoplastic polymer is selected from the group consisting ofpolypropylene; polyamide; saturated polyester; including polyethyleneterephthalate and polybutylene terephthalate; polystyrene; phenoxy;polyphenylene oxide; polyphenylene sulfide, polycarbonate, andacrylonitrile, styrene-butadiene-terpolymers.
 25. Aqueous sizingcomposition for glass fibers produced in wet chopped forming process toreinforce thermoplastic polymer, comprising in weight percent of theaqueous sizing composition:a. about 0.1 to about 10 weight percent ofsubstantially aliphatic and/or alicyclic polyurethane polymer havingcarboxyl moieties, b. about 0.1 to about 10 weight percent of apolyepoxide polymer with a molecular weight in the range of about 170 toabout 900 wherein the weight ratio of the polyurethane to the epoxypolymer is about 5 to about 1 to about 1 to about 5, c. about 0.1 toabout 7 weight percent of an aqueous dispersible, emulsifiable orsolubilizable high density polyethylene polymer, d. about 0.01 to about6 weight percent of a microcrystalline paraffinic wax having a meltingpoint above about 50° C., wherein the weight ratio of the polyethylenepolymer to the wax is in the range of about 25 to 1 to about 1 to 25, e.mixture of silane coupling agents in an amount of about 0.1 to about 2weight percent with a predominant amount beinggamma-aminopropyltriethoxysilane, and with a minor amount beinggamma-glycidoxypropyl-trimethoxysilane and with the smallest amountbeing a lubricant modified gamma-aminopropyltriethoxy silane, f. waterin an amount sufficient to give a total solids for the aqueous sizingcomposition in the range of about 2 to about 20 weight percent. 26.Chopped glass fiber strands having the dried residue of the aqueoussizing composition of claim
 25. 27. An aqueous sizing composition fortreating glass fibers useful in reinforcing thermoplastic polymers,comprising:a. polyurethane polymer, b. epoxy polymer, c.polyethylene-containing polymer with limited branching, d. amino-silanecoupling agent, and e. water in an amount to give a total solids for thecomposition in the range of 1 to about 30 weight percent.
 28. Glassfibers sized with the aqueous treating composition of claim 27.